The PPA for Popcorn Time has been removed, but you can still download it and use it on your system. Please note that it may be illegal to use Popcorn Time in your country, so if you choose to use Popcorn Time, use it at your own risk. Also, there are several spin-offs of Popcorn Time. It's recommended that you download it from the official site...

All you have to do is click on the file --> Popcorn-TimeThat will bring up the Popcorn Time interface, and you can then watch it.

This doesn't install it on your system. If you don't want to have to click on that file each time you want to watch Popcorn Time, you can add it to your menu with the Menu Editor (Menulibre) included with ChaletOS (as shown in the video below).